It’s Fair to Ask: Is the Republican Race Over?

Is the Republican presidential primary over already?

Not quite, but it’s a reasonable question after New Hampshire’s first-in-the-nation primary delivered a clear victory for Donald J. Trump on Tuesday night. And if your definition of “over” is whether Mr. Trump is now on track to win without a serious contest, the answer is probably “yes.”

With nearly all the counting done, he won 55 percent of the vote. His only remaining rival, Nikki Haley, won 44 percent.

Mr. Trump’s 11-point margin of victory is not extraordinarily impressive in its own...